Question

Solve each system using the substitution method.
y= 2x
5x - y =9

Answer 1

{y,x}={6,3}

Explanation

System of Linear Equations entered :

[1] y=2x

[2] 5x-y=9

Equations Simplified or Rearranged :

[1] y - 2x = 0

[2] -y + 5x = 9

Graphic Representation of the Equations :

-2x + y = 0 5x - y = 9

Solve by Substitution :

// Solve equation [1] for the variable y

[1] y = 2x

// Plug this in for variable y in equation [2]

[2] -(2x) + 5x = 9

[2] 3x = 9

// Solve equation [2] for the variable x

[2] 3x = 9

[2] x = 3

// By now we know this much :

y = 2x

x = 3

// Use the x value to solve for y

y = 2(3) = 6

Solution :

{y,x} = {6,3}